Yamaha YFM660RN Service Manual page 288

Spark plug gap:
0.8 ~ 0.9 mm (0.031 ~ 0.035 in)
For USA and CDN
4.Ignition spark gap
Disconnect the spark plug cap from the
spark plug.
Connect the dynamic spark tester 1 as
shown.
2 Spark plug cap
3 Spark plug
Turn the main switch to "ON".
Check the ignition spark gap.
Crank the engine by pushing the starter
switch, and increase the spark gap until a
misfiring occurs.
Minimum spark gap:
6.0 mm (0.24 in)
For Europe
4.Ignition spark gap
Disconnect the spark plug cap from the
spark plug.
Connect the ignition checker 1 as shown.
2 Spark plug cap
Turn the main switch to "ON".
Check the ignition spark gap a.
Crank the engine by pushing the starter
switch, and increase the spark gap until a
misfiring occurs.
Minimum spark gap:
6.0 mm (0.24 in)
*
CORRECT
OUT OF
SPECIFICATION
OR NO SPARK
8 - 7
IGNITION SYSTEM
INCORRECT
Repair or replace the spark plug.
MEETS SPECIFICATION
The ignition system is not faulty.
MEETS SPECIFICATION
The ignition system is not faulty.
– +
ELEC